A New Pretreatment Method for Toolmarks on Bone

Toolmark on bone was selected as research object and a new pretreatment method on defatting bone was developed in this paper. The study aims to enhance the characteristics of toolmarks on bone and extend the storage time of similar evidence. The pig claviform bone was selected as the experimental material to generate the tested tool marks. A total of 30 samples were made by the pig bones being sawn with a steel saw and real conditions simulated for toolmarks in crime scene. The influences of different types of organic solvent, steps of defatting and time of treatment on features of toolmarks on bone and defatting ratio were analyzed with simulating experiments in laboratory. The organic solvent, steps of defatting and treatment time were optimized, and a new and effective pretreatment method for defatting bone by absolute alcohol, petroleum benzin and infrared drying was developed. Instead of destroying the features of toolmarks, the method could enhance the contrast of striation present on fracture surface of bone, convenient for further recovering and examining toolmarks on bone by photography. Meanwhile, no pungent smell was produced from a defatted bone after long storage in glassware. This paper presents a new pretreatment technique of defatting bone to safeguard further toolmark determination and storage of evidence.